The present invention relates to a method for the post-processing of sheets processed by a sheet processing apparatus provided with a sheet punching device for punching a set of two or more spaced holes in sheets, wherein the method includes the step of punching the set of holes in all sheets of a first batch, in a first, standard, position, wherein the sheets of the first batch have substantially equal size and orientation.
The present invention also relates to a sheet processing apparatus provided with a sheet punching device for punching holes in a sheet member such as a sheet of paper (hereafter referred to as a sheet).
Sheet punching devices are typically installed in a sheet processing apparatus such as a printer, a photocopying machine, a facsimile or a sheet post processing apparatus connected with an image processing apparatus. The sheet processing apparatus may perform several post-processing operations including, for example, a stack operation for stacking sheets on an output tray, a staple operation for stapling sets of sheets, and a punching operation for punching a sheet or sheets with the sheet punch device.
Background sheet punch devices are divided into two types depending on the driving method for driving a punch to create a hole in a sheet, i.e., (1) a press punch method and (2) a rotary punch method. Both types of punch devices can be used in connection with the present invention.
U.S. Pat. No. 6,120,015 discloses a press punch-type sheet punching device for punching holes in sheets outputted by a printing system, with a common sheet entrance path, two separate but closely vertically superposed sheet paths, a gating system alternately gating the unpunched sheets into one of said two separate sheet paths having respective separate (but shared) components, sheet punching stations with common reciprocally, vertically driven sheet punches. The sheets are alternately stopped and the desired hole patterns are alternately punched, and the sheets ejected, in the two separate sheet paths, individually punched, or punched simultaneously as stacked sets.
U.S. Pat. No. 6,305,262 discloses a sheet punch device including one or more punching units having a rotatable punch that punches a hole in a sheet, a driving member that drives and rotates the punch member to punch a hole in a conveyed sheet, and in which the punch member punches holes in the conveyed sheet at plural places aligned in a sheet conveying direction. Also included is a control device that controls the driving member such that the punch member punches a predetermined number of holes in the conveyed sheet sequentially at predetermined positions aligned in the sheet conveying direction. The punch units may be displaced to adapt to different paper sizes and/or and hole configurations selected by an operator. The sheet punch device is part of a post processing apparatus of an image forming device. Via a graphical user interface an operator can select the number of holes per sheet from a number of standard configurations (i.e. two, three, four or five holes per sheet). The user interface also allows the operator to choose for the holes to be aligned along the height or along the width of the sheet. These choices are limited to a number of standardized positions.
Generally, punching holes in documents for filing purposes is governed by a number of national and international standards such as International standard ISO 838, US military standard MIL-STD-1160 (FSC 7530) and German industry standard DIN 821. Other national standards exist and are in use.
U.S. Pat. No. 6,065,383 also discloses a punching mechanism displaceable to any of a plurality of punching positions in order to correctly punch holes in the standardized positions in different paper sizes.